Seismic modeling is a useful tool for studying the propagation of seismic waves within complex structures. However, traditional methods of seismic simulation cannot meet the needs for studying seismic wavefields in th...Seismic modeling is a useful tool for studying the propagation of seismic waves within complex structures. However, traditional methods of seismic simulation cannot meet the needs for studying seismic wavefields in the complex geological structures found in seismic exploration of the mountainous area in Northwestern China. More powerful techniques of seismic modeling are demanded for this purpose. In this paper, two methods of finite element-finite difference method （FE-FDM） and arbitrary difference precise integration （ADPI） for seismic forward modeling have been developed and implemented to understand the behavior of seismic waves in complex geological subsurface structures and reservoirs. Two case studies show that the FE-FDM and ADPI techniques are well suited to modeling seismic wave propagation in complex geology.展开更多
To improve the accuracy of the conventional finite-difference method, finitedifference numerical modeling methods of any even-order accuracy are recommended. We introduce any even-order accuracy difference schemes of ...To improve the accuracy of the conventional finite-difference method, finitedifference numerical modeling methods of any even-order accuracy are recommended. We introduce any even-order accuracy difference schemes of any-order derivatives derived from Taylor series expansion. Then, a finite-difference numerical modeling method with any evenorder accuracy is utilized to simulate seismic wave propagation in two-phase anisotropic media. Results indicate that modeling accuracy improves with the increase of difference accuracy order number. It is essential to find the optimal order number, grid size, and time step to balance modeling precision and computational complexity. Four kinds of waves, static mode in the source point, SV wave cusps, reflection and transmission waves are observed in two-phase anisotropic media through modeling.展开更多
The arbitrary Lagrangian-Eulerian（ALE） adaptive remeshing technology and the HyperXtrude software of transient finite element simulations were used on analogue simulation of aluminium extrusion processing.The field ...The arbitrary Lagrangian-Eulerian（ALE） adaptive remeshing technology and the HyperXtrude software of transient finite element simulations were used on analogue simulation of aluminium extrusion processing.The field distributions of strain rate,stress,temperature and velocity of metal flow were obtained.The results are basically consistent with the experiment,which indicates that this method may successfully predict the defects in the actual extrusion process.展开更多
To determine the procedure-related factors that affect sedation satisfaction and to make a suggestion to improve it.METHODSWe prospectively enrolled a total of 456 patients who underwent outpatient endoscopy procedure...To determine the procedure-related factors that affect sedation satisfaction and to make a suggestion to improve it.METHODSWe prospectively enrolled a total of 456 patients who underwent outpatient endoscopy procedures with midazolam sedation between March 2014 and August 2014. All patients completed both pre- and post-endoscopy questionnaires about sedation expectations and satisfaction.RESULTSThe study cohort included 167 (36.6%) patients who underwent esophagogastroduodenoscopy (EGD), 167 (36.6%) who underwent colonoscopy, and 122 (26.8%) who underwent a combined procedure (EGD and colonoscopy). Over 80% of all patients were satisfied with sedation using midazolam. In univariate and multivariate analyses, total procedure time in the EGD group, younger age (≤ 50 years), and longer colonoscopy withdrawal time in the colonoscopy group were related to decreased satisfaction with sedation. However, in active monitoring and intervention group, there was no decrease in grade of satisfaction despite longer procedure time due to more procedures during colonoscopy. Younger age (≤ 50 years), longer inter-procedure time gap, and colonoscopy withdrawal time were related to decreased satisfaction in the combined EGD and colonoscopy group.CONCLUSIONMidazolam is still a safe and effective sedative for gastrointestinal endoscopy. Satisfaction with sedation depends on several factors including age (≤ 50 years) and procedure time duration. To improve patient satisfaction with sedation, active monitoring of sedation status by the endoscopist should be considered for patients who require long procedure time.展开更多
基金supported by the Natural Science Foundation of China(Grant No.40574050,40821062)the National Basic Research Program of China(Grant No.2007CB209602)the Key Research Program of China National Petroleum Corporation(Grant No.06A10101)
文摘Seismic modeling is a useful tool for studying the propagation of seismic waves within complex structures. However, traditional methods of seismic simulation cannot meet the needs for studying seismic wavefields in the complex geological structures found in seismic exploration of the mountainous area in Northwestern China. More powerful techniques of seismic modeling are demanded for this purpose. In this paper, two methods of finite element-finite difference method （FE-FDM） and arbitrary difference precise integration （ADPI） for seismic forward modeling have been developed and implemented to understand the behavior of seismic waves in complex geological subsurface structures and reservoirs. Two case studies show that the FE-FDM and ADPI techniques are well suited to modeling seismic wave propagation in complex geology.
文摘To improve the accuracy of the conventional finite-difference method, finitedifference numerical modeling methods of any even-order accuracy are recommended. We introduce any even-order accuracy difference schemes of any-order derivatives derived from Taylor series expansion. Then, a finite-difference numerical modeling method with any evenorder accuracy is utilized to simulate seismic wave propagation in two-phase anisotropic media. Results indicate that modeling accuracy improves with the increase of difference accuracy order number. It is essential to find the optimal order number, grid size, and time step to balance modeling precision and computational complexity. Four kinds of waves, static mode in the source point, SV wave cusps, reflection and transmission waves are observed in two-phase anisotropic media through modeling.
基金Project (2009A080205003) supported by the Major Science and Technology Project of Guangdong Province,ChinaProject (30815009) supported by the Foundation of State Key Laboratory of Advanced Design and Manufacture for Vehicle Body,China
文摘The arbitrary Lagrangian-Eulerian（ALE） adaptive remeshing technology and the HyperXtrude software of transient finite element simulations were used on analogue simulation of aluminium extrusion processing.The field distributions of strain rate,stress,temperature and velocity of metal flow were obtained.The results are basically consistent with the experiment,which indicates that this method may successfully predict the defects in the actual extrusion process.
文摘To determine the procedure-related factors that affect sedation satisfaction and to make a suggestion to improve it.METHODSWe prospectively enrolled a total of 456 patients who underwent outpatient endoscopy procedures with midazolam sedation between March 2014 and August 2014. All patients completed both pre- and post-endoscopy questionnaires about sedation expectations and satisfaction.RESULTSThe study cohort included 167 (36.6%) patients who underwent esophagogastroduodenoscopy (EGD), 167 (36.6%) who underwent colonoscopy, and 122 (26.8%) who underwent a combined procedure (EGD and colonoscopy). Over 80% of all patients were satisfied with sedation using midazolam. In univariate and multivariate analyses, total procedure time in the EGD group, younger age (≤ 50 years), and longer colonoscopy withdrawal time in the colonoscopy group were related to decreased satisfaction with sedation. However, in active monitoring and intervention group, there was no decrease in grade of satisfaction despite longer procedure time due to more procedures during colonoscopy. Younger age (≤ 50 years), longer inter-procedure time gap, and colonoscopy withdrawal time were related to decreased satisfaction in the combined EGD and colonoscopy group.CONCLUSIONMidazolam is still a safe and effective sedative for gastrointestinal endoscopy. Satisfaction with sedation depends on several factors including age (≤ 50 years) and procedure time duration. To improve patient satisfaction with sedation, active monitoring of sedation status by the endoscopist should be considered for patients who require long procedure time.
